Metal oxide semiconductor (MOS) transistors with increased break down voltages and methods of making the same
First Claim
1. A transistor comprising:
- a substrate of a first conductivity type and having a first doping concentration;
a drain region and a source region of a second conductivity type and disposed in said substrate;
a gate separated from said substrate by a gate oxide layer and placed between said source region and said drain region;
an adjustment implant region of said first conductivity type and disposed under said gate oxide layer and in said substrate, said adjustment implant region having a second doping concentration higher than said first doping concentration; and
a planar junction formed between said adjustment implant region and said drain region, said adjustment implant region and said drain region being in a predetermined shape to form said planar junction with a surface curvature pointing towards said drain region to relax electrical field intensity at a location of said planar junction.
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Accused Products
Abstract
A transistor comprises a substrate of a first conductivity type, a drain region and a source region of a second conductivity type, a gate, a gate oxide layer, an adjustment implant region of the first conductivity type and a planar junction. The drain region and the source region are disposed in the substrate. The gate is placed over the substrate between the source region and the drain region. The gate is separated from the substrate by the gate oxide layer. The adjustment implant region is disposed under the gate oxide layer and in the substrate. A second doping concentration of the adjustment implant region is higher than a first doping concentration of the substrate. The adjustment implant region and the drain region in a predetermined shape form the planar junction with a surface curvature pointing towards the drain region to relax electrical field intensity at a location of the planar junction.
8 Citations
22 Claims
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1. A transistor comprising:
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a substrate of a first conductivity type and having a first doping concentration; a drain region and a source region of a second conductivity type and disposed in said substrate; a gate separated from said substrate by a gate oxide layer and placed between said source region and said drain region; an adjustment implant region of said first conductivity type and disposed under said gate oxide layer and in said substrate, said adjustment implant region having a second doping concentration higher than said first doping concentration; and a planar junction formed between said adjustment implant region and said drain region, said adjustment implant region and said drain region being in a predetermined shape to form said planar junction with a surface curvature pointing towards said drain region to relax electrical field intensity at a location of said planar junction. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for fabricating a transistor, comprising:
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providing a substrate of a first conductivity type and having a first doping concentration; forming a source region and a drain region of a second conductivity type in said substrate; placing a gate over said substrate and between said source region and said drain region; separating said gate from said substrate by a gate oxide layer; forming an adjustment implant region under said gate oxide layer and in said substrate, said adjustment implant region being of said first conductivity type and having a second doping concentration higher than said first doping concentration; and forming a planar junction between said adjustment implant region and said drain region, said adjustment implant region and said drain region being in a predetermined shape to form said planar junction with a surface curvature pointing towards said drain region to relax electrical field intensity at a location of said planar junction. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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Specification